In the context of food shopping (Unit 6, Section 3), "piece" is used to describe portions of food: — used to mean "a slice of cake".
Английский язык 4 класс 2017 2018 - Calaméo angliiskii iazyk 4 klass rabochaia tetrad 1 biboletova
— appearing in reading dialogues, such as Miss Chatter offering "a nice piece of bread and butter". Related Vocabulary (Unit 6) In the context of food shopping (Unit 6,
Students often study "piece" alongside other containers and quantities used for shopping: (juice/water) A bottle of (water) A box of (chocolates) A bag of (sweets) A cup of (tea) In the by M
— often found in exercises requiring students to match containers/quantities with products.
In the by M.Z. Biboletova (Enjoy English), the word " piece " primarily appears in Unit 6, which focuses on shopping for food and clothing. Common Uses of "Piece" in the Workbook